Apparatus for the electrolytic production of metallic alloys in the form of paste orsludge



1,461,276 B. LEECH YTIC PRODUCTION OF METALLIC ALLOYS July 10, 1923.

2 Sheets-Sheet 1 L BETA Filed March 16 1920 IN THE FORM OF PASTE OR SLUDGE APPARATUS FOR THE ELECTROL Wag S July 10, 1923. 1.461.276

B. LEEC APPARATUS FOR THE ELECTROLYTIC PRODUCTION OF METALLIC ALLOYS Y IN THE FORM OF PASTE OR SLUDGE Filed March 16, 1920 2 Sheets-Sheet Z Patented July 10, 1923.

UNlTED STATES PATENT OFFICE.

BENJAMIN LEECH, OF KACCLESFIELD, ENGLAND, ASSIGNOR OF ONE-HALF TO HENRY & LEIGH SLATER, LIMITED, 01'' MANCHESTER, ENGLAND.

APPARATUS FOR THE ELECTROLYTIC PRODUCTION OF METALLIC ALLOYS IN THE FORM OF PASTE OR SLUDGE.

Application filed March 16, 1920. Serial No. 366,327.

To all whom it may concern:

Be it known that I, BENJAMIN Lnnon, a subject of the King of Great- Britain and Ireland, and residing at 77 Pownall Street,

5 Macclesfield, in the county of Chester, England, have invented certain new and useful Improvements in and Relating to' Apparatus for the Electrolytic Production of Metallic Alloys in the Form of Paste or Sludge, for which I have filed. an application in reat Britain, on Dec. 28, 1917, granted March 20, 1918, and numbered 124,006), of

which the following is a specification.

This invention relates to the electrolytic preparation of metals or alloys in the form of paste or sludge, and its object is to prepare such material .in the desired physical condition to suit the purpose for which it is to be used.

For many purposes it is necessary that there should be little or no variation in the size of the particles deposited at the cathode; for example, in the production of tin paste, if the particles are too fine or too coarse, a paper coated therewith does not have the best possible appearance. The burnishing quality of paper coated with the paste is directly dependent on the size of the particles.

In the electrolytic pre aration of tin paste it is usual to keep the e ectrolyte in circulation, so as to keep at any instant the concentration of stannous chloride or electrolytic solution uniform throughout the electrolytic vat or vats. The circulation also tends to maintain at any instanha uniform temperature throughout the electrolytic solution. But even with these precautions the temperature of the electrolyte may vary from time to time, and the percentage of stannous chloride in the electrolyte gradually varies, owing to the fact that hydrogen is produced at the cathode simultaneously with the tin, and an excess of tin goes into solution at the anode over and above that deposited at the cathode, such excess of tin being approximately chemically equivalent to the hydrogen liberated at the cathode. The character of the tin deposited at the cathode is intimately associated with the character and amount of the hydrogen production, so that all attempts to reduce the amount of hydroliberated cause changes in the character of the tin deposit. In general, the less the hydro en liberated the coarser are the tin part1c es.

The present invention consists in using in the electrolytic preparation of metals or alloys in the form of paste or sludge anodes formed partly of the active metal and partly of a material (for example, hard graphite) which resists or withstands the conditions of electrochemical action and does not disintegrate nor pass into solution.

The invention also consists in means for varying or adjusting the ratio of the areas of the active and resistant portions of the anode immersed in the electrolyte.

The invention also consists in employing a grou of vats through which one and the same e ectrolyte is circulated, the vats being electrically connected in series or in parallel, or supplied with current independently, as the conditions require. Active and resistant material for the anodes may be used in the same vat or vats, or active and resistant anodes may be arranged in separate vats.

The invention further consists in means for controlling or regulating the fiow'of the electrolyte through any vat or vats of such group.

The invention also consists in employing a heating or coolin coil or the like in combination with the e ectrolytic vat or vats and the circulating means.

I will now describe the invention in connection with the accompanying drawings in which:

Figure 1 is a dlagrammatic top plan view of one form of the invention.

Fig. 2 is a diagrammatic sectional view showing means for varying the depth of immersion of the active and resistant materials of the anodes.

Fig. 3 is a diagrammatic view showing an apparatus including a plurality of electrolyte vats, means for circulating and regulating the passage of the electrolyte through the vats and means for altering the tempera ture of the electrolyte.

In the embodiment of the. invention illustrated in Fig. 1, C designates the electro lyte vat or tank provided with three anodes C? and two cathodes C. The anodes in this case being formed of pieces of active material T such as tin and pieces of resisting material G such as graphite.

In the form of the invention shown in Fig. 2, means are illustrated for varying the proportion of the active material to the resistant material which are immersed in the electrolyte contained in the tank L.

This figure of the drawings shows a vertical section through a tank in which three active or tin anodes T-T and T cooperate with two resistant anodes such as graphite G and G The anodes are counterpoised by weights \V suspended over pulleys P so that the area of any anode exposed beneath the surface of the solution (shown by the dotted line L) can be varied.

In the embodiment of the invention shown in Fig. 3 two electrolyte tanks D and D are shown, of which the tank D contains three tin anodes T and the tank D three graphite anodes G Circulation of the electrolyte is provided through the spiral coil S cooled or heated by a stream of water or the like in the tank D The circulation is maintained by a pump P. A is the main suction pipe and a and a branches therefrom to the tanks D and D respectively. B is the main discharge pipe with similarbranches Z) and b Taps or valves 6', 15 and t* provide means for regulating the flow of electrolyte and adjusting the valves thereof in the tanks.

I am aware that the combined action of soluble and non-soluble anodes has been employed in the electroplating of metal surfaces, and in the electrode-position of spongy metal, for example, in the electrode-position of spongy lead on the supporting plates or grids of storage batteries, or in the electrolytic production of coherent metal wires or sheets. My invention does not deal with such manufactures, the particles of paste or sludge produced by my invention having little or no coherence between themselves or to the cathode.

In carrying out the invention, I make the ratio of the active to the resistant areas of the anode such as we find on trial leads to a constant concentration of the metallic salt in the electrolyte under the required conditions. This may be effected by removing an active part of the anode, and adding a resistant part, or vice versa, as becomes necessary from time to time to keep the variation in the concentration within the permissible limits, or by so directing and controlling the flow of the electrolytic solution or of the electric current in a group of vats, that the effective proportion of active to resistant anode area is increased or diminished according as it is necessary to increase or diminish the concentration of the metallic salt in the electrolyte. Such control of the electric current may be eflective by means of a suitable system of wiring and switches. Such control of the flow of electrolyte may be effected by means of the system of piping and valves shown in Fig. 3. The means for raising and lowering the active and resistant parts of the anode relative to the level of the electrolyte in the vat or vats is provided, in order that the ratio of the areas of the two parts of the anode may be quickly adjusted to any required value.

The paste or sludge deposited at the cathode has little or no coherence in itself or to the cathode, and is periodically removed in bulk therefrom by scraping or other suitable means when a suflicient accumulation has taken place.

As an additional means of regulating the concentration of metallic salt in the electrolyte, the active metal, in plates or other convenient form, may be suspended from time to time in the electrolytic solution and allowed to dissolve chemically without being directly connected to the anodes.

The electrolyte is circulated through the heating or cooling coils, to maintain the temperature constant during the whole time of electrolytic deposition.

As an example of a suitable adjustment of the conditions for obtaining one desired quality of tin sludge, but not as a limitation, I give the following particulars Tin, 2.5 grammes per litre.

Total acidity; as hydrochloric acid, 50 grammes per litre.

Current density: 0.6 amperes per square centimetres of cathode.

Ratio of areas of active (tin) anode and resistant (carbon) anode 2.4.

Temperature; not above 28 (3., preferably about 20-21 C.

The production of tin paste has been above referred to, as this is one application of my invention; my invention may be applied for the production of other similar metals or alloys, e. g. copper or bronzes in the form of paste or sludge.

Having now described my invention, what- I claim as new and desire to secure by Letters Patent is 1. In an a paratus for the electrolytic preparation 0? metal or alloys in the form of paste or sludge, a vat containing electrolyte, and anodes located in said vat and formed partly of an active material and partly of a material which resists or withstands the conditions of electro-chemical action and does not disintegrate or pass into solution, said active material and the resistant material being immersed in and contacting with said electrolyte.

2. In an apparatus for the electrolytic preparation of metals, 01' alloys in the form of paste or sludge, a vat containing electrolyte, and anodes located in said vat and formed partly of an active metal and artly of graphite, said active metal and said graphite being immersed in and contacting with said electrolyte.

3. In an apparatus as set forth in claim 1, means for varying or adjusting the ratio of the areas of the active material and the resistant material of the anodes immersed in the electrolyte.

4. In an apparatus as set forth in claim 2, means for varying or adjusting the ratio of the areas of the active metal and the graphite of the anodes immersed in the electrolyte.

5. In an apparatus for the electrolytic preparation of metals or alloys in the form of paste or sludge, a plurality of vats containing electrolyte, means for circulatin the electrolyte through said vats, and anodes located in said vats and formed partly of active material and partly of a material which resists or withstands the conditions of electro-chemical action and does not pass into solution, said active material and the resisting material being immersed in the electrolyte and {contacting therewith.

6. In an apparatus as set forth in claim 5, anodes of the active material located in one of said vats and anodes of resistant material located in another of said vats.

7. An apparatus of the kind defined by claim 5 having means for controlling or regulating the flow of electrolyte through one or all of the vats.

8. An apparatus of the kind defined by claim 5 provided with temperature regulating means through which the electrolyte is circulated.

In testimony whereof I have signed my name to this specification.

BENJAMIN LEECH. 

